1. Field of the Invention
The present invention relates to electromagnetic detachable connectors for electrical connection between electronic devices, precision apparatuses, medical equipment, and the like including semiconductor devices such as LSIs that have a pair of connectors including a female connector and a male connector connected in a detachable manner by electromagnetic force, or for connection of devices in water, air, at high and low temperatures, and in confined locations. More particularly, the present invention relates to an electromagnetic detachable connector suitable as a microconnector that can be used in the field of micromachines where a connector in the submicron range and having high contact density is required.
2. Description of the Background Art
Reduction in the size of apparatuses has seen significant development these past few years particularly in the field of information communication equipment such as hard discs, CD memories, notebook type personal computers, ink jet printers, and the like. Accordingly, the demand for miniaturization in the wiring portion of these apparatuses is great. Miniaturization of connectors is in progress in memory cards and input/output control cards for notebook type personal computers.
As a technique of producing microminiaturization components, a LIGA process is known in which a series of processes such as X-ray lithography, plating, and molding are carried out. For example, a prototype by MicroParts GmbH (Germany) is described in J. Micromech. Microeng. Vol. 2, p. 133 as an example of a microconnector formed according to the LIGA process.
FIG. 11 is a schematic diagram of the connecting portion of this prototype. An enlargement of a female connector electrode 65 and a male connector electrode 66 of FIG. 11 is shown in FIG. 12. Referring to FIG. 11, this microconnector has female connector electrode 65 and male connector electrode 66 connected by fitting a guide pin 70 (1 mm.times.2 mm.times.0.25 mm) on a male connector 68 into a guide hole 69 in a female connector 67, whereby the microconnector is mechanically maintained in a connected state.
In connecting female connector electrode 65 and male connector electrode 66 in a microconnector of the above-described structure, critical alignment is required in the positional registration. The operation of connection/disconnection had to be carried out by direct manipulation by an operator visually using a microscope or externally using a drive device of a particular design. Thus, there was a problem that critical positioning and control of the driving force required for connection/disconnection of the connector are difficult to achieve according to the conventional connection technique of high contact density used in micromachines.
Aiming to solve the above conventional problem, a microconnector is proposed by the same applicant as that of the present invention in U.S. patent application Ser. No. 08/788,889 (filed Jan. 21, 1997). This microconnector maintains terminal connection in the connected state of the connectors by virtue of attraction of a permanent magnet. The structure of this microconnector is shown in FIGS. 12A, 12B, 12C and 12D.
Referring to FIGS. 12B and 12D, a male connector 23 has a plurality of wiring layers 26 formed of deposited conductive materials on a substrate 25. A male connector electrode 24 formed of a conductive material protrudes from one end of wiring layer 26. The leading end of pin electrode 24 is tapered. As shown in FIG. 12B, electrodes 24 are arranged not linearly, but in a two dimensional manner, for example in a matrix, on substrate 25. Respective electrodes 24 are surrounded by a spacer 27.
Referring to FIGS. 12A and 12C, a female connector 15 has a plurality of wiring layers 18 formed of deposited conductive materials on a substrate 17. A female connector electrode 16 is formed at each one end of wiring layer 18. Female connector electrodes 16 formed of a conductive material are arranged in a two dimensional manner, for example in a matrix, so as to correspond to pin electrodes 24 shown in FIG. 12B. Each female connector electrode 16 has a hole 16a to receive pin electrode 24 for electrical connection. Female connector electrode 16 is surrounded by a spacer 19.
Male connector 23 of FIG. 12B and female connector 15 of FIG. 12A are electrically connected by overlaying the plane of substrates 25 and 17 where respective electrodes are formed so as to face each other. Here, positioning of male connector electrode 24 and female connector electrode 16 is implemented by aligning a magnetic layer 28 provided on male connector 23 with a magnetic layer 20 provided on female connector 15. Magnetic layers 28 and 20 each forming a permanent magnet attract each other to join the connectors.
In the above microconnector employing the attraction of a permanent magnet, the attraction between the permanent magnets is significantly reduced with increasing distance therebetween. Although the connection between the female connector and the male connector can be maintained, attraction of a sufficient level is not generated between the permanent magnets to move the female and male connectors unless they are close enough to each other for achieving the required magnetic attraction when the connectors are moved closer or farther away from each other. It was not possible to take advantage of the attraction of the permanent magnet at greater distances. As a result, manual operation was required. In the environment where direct manual operation was not available, it was difficult to carry out the connection/disconnection operation.
There was also a problem that a rather high force had to be exerted externally for detaching the female and male connectors from each other by overcoming the great attraction between the permanent magnets of the connected female connector and male connector.